我正在学习 Spring 安全。我开发了一个通过cas进行身份验证的应用程序。我从本教程的示例开始：https://www.baeldung.com/spring-security-cas-sso.
WebSecurity配置文件的内容是：

@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    private Logger logger = LoggerFactory.getLogger(WebSecurityConfig.class);
    private SingleSignOutFilter singleSignOutFilter;
    private LogoutFilter logoutFilter;
    private CasAuthenticationProvider casAuthenticationProvider;
    private ServiceProperties serviceProperties;

    @Autowired
    public WebSecurityConfig(SingleSignOutFilter singleSignOutFilter, LogoutFilter logoutFilter,
                             CasAuthenticationProvider casAuthenticationProvider,
                             ServiceProperties serviceProperties) {
        this.logoutFilter = logoutFilter;
        this.singleSignOutFilter = singleSignOutFilter;
        this.serviceProperties = serviceProperties;
        this.casAuthenticationProvider = casAuthenticationProvider;
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().antMatchers( "/secured", "/login").authenticated()
          .and()
          .exceptionHandling().authenticationEntryPoint(authenticationEntryPoint())
          .and()
          .addFilterBefore(singleSignOutFilter, CasAuthenticationFilter.class)
          .addFilterBefore(logoutFilter, LogoutFilter.class)
          .csrf().ignoringAntMatchers("/exit/cas");
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.authenticationProvider(casAuthenticationProvider);
    }

    @Bean
    @Override
    protected AuthenticationManager authenticationManager() throws Exception {
        return new ProviderManager(Collections.singletonList(casAuthenticationProvider));
    }

    public AuthenticationEntryPoint authenticationEntryPoint() {
        CasAuthenticationEntryPoint entryPoint = new CasAuthenticationEntryPoint();
        entryPoint.setLoginUrl("http://cas-docker:7080/cas/login");
        entryPoint.setServiceProperties(serviceProperties);
        return entryPoint;
    }

}

spring应用程序文件的内容是：

@SpringBootApplication
public class CasSecuredApplication extends SpringBootServletInitializer {

    private static final Logger logger = LoggerFactory.getLogger(CasSecuredApplication.class);

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(CasSecuredApplication.class);
    }

    public static void main(String... args) {
        SpringApplication.run(CasSecuredApplication.class, args);
    }

    @Bean
    public CasAuthenticationFilter casAuthenticationFilter(
      AuthenticationManager authenticationManager,
      ServiceProperties serviceProperties) throws Exception {
        CasAuthenticationFilter filter = new CasAuthenticationFilter();
        filter.setAuthenticationManager(authenticationManager);
        filter.setServiceProperties(serviceProperties);
        return filter;
    }

    @Bean
    public ServiceProperties serviceProperties() {
        logger.info("service properties");
        ServiceProperties serviceProperties = new ServiceProperties();
        serviceProperties.setService("https://tomcat-docker:8443/cas-secured-app-0.0.1-SNAPSHOT/login/cas");
        serviceProperties.setSendRenew(false);
        return serviceProperties;
    }

    @Bean
    public TicketValidator ticketValidator() {
        return new Cas30ServiceTicketValidator("http://cas-docker:7080/cas");
    }

    @Bean
    public CasAuthenticationProvider casAuthenticationProvider(
      TicketValidator ticketValidator,
      ServiceProperties serviceProperties) {
        CasAuthenticationProvider provider = new CasAuthenticationProvider();
        provider.setServiceProperties(serviceProperties);
        provider.setTicketValidator(ticketValidator);
        provider.setUserDetailsService(
          s -> new User("test@test.com", "Mellon", true, true, true, true,
          AuthorityUtils.createAuthorityList("ROLE_ADMIN")));
        provider.setKey("CAS_PROVIDER_LOCALHOST_8900");
        return provider;
    }

    @Bean
    public SecurityContextLogoutHandler securityContextLogoutHandler() {
        return new SecurityContextLogoutHandler();
    }

    @Bean
    public LogoutFilter logoutFilter() {
        LogoutFilter logoutFilter = new LogoutFilter("https://tomcat-docker:8443/logout", securityContextLogoutHandler());
        logoutFilter.setFilterProcessesUrl("/logout/cas");
        return logoutFilter;
    }

    @Bean
    public SingleSignOutFilter singleSignOutFilter() {
        SingleSignOutFilter singleSignOutFilter = new SingleSignOutFilter();
        singleSignOutFilter.setLogoutCallbackPath("/exit/cas");
        singleSignOutFilter.setIgnoreInitConfiguration(true);
        return singleSignOutFilter;
    }

}

当我访问/登录时，会重定向到cas保护区。然后，将显示登录屏幕，输入名称和密码，然后单击登录会话按钮。之后，cas重定向到此url：

https://tomcat-docker:8443/cas-secured-app-0.0.1-SNAPSHOT/login/cas?ticket=ST-10-23dDew2ztSMwkbEXgtDC-9086a9962d01

在此之后，获得以下误差：

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.
Fri May 21 10:24:12 UTC 2021
There was an unexpected error (type=Internal Server Error, status=500).

此链接https://docs.spring.io/spring-security/site/docs/4.2.x/reference/html/cas.html 提到筛选器始终侦听对/login/cas的请求。
为什么过滤器不侦听/login/cas并继续验证过程？代码中缺少什么吗？
更新：
cas服务器日志显示以下内容：

2021-05-21 12:43:56,544 INFO [org.apereo.inspektr.audit.support.Slf4jLoggingAuditTrailManager] - <Audit trail record BEGIN

=============================================================

WHO: casuser

WHAT: ST-18-snPFz6n5AdakHvBpROlf-9086a9962d01 for https://localhost:8443/login/cas

ACTION: SERVICE_TICKET_CREATED

APPLICATION: CAS

WHEN: Fri May 21 12:43:56 UTC 2021

CLIENT IP ADDRESS: 172.19.0.1

SERVER IP ADDRESS: 172.19.0.6

=============================================================

在属性文件中，我将：

server.servlet.contextPath=/cas-secured-app-0.0.1-SNAPSHOT

cas服务器配置为默认配置。我没有碰它。
为什么cas服务器说它正在侦听https://localhost:8443/login/cas? 是否需要配置cas服务器？